摘要
采用真空电弧熔炼技术制备了CoCrFeNiW_(x)(x=0.25、0.5、0.75及1.0)系列高熵合金,研究了W元素含量对合金晶体结构、显微组织、力学性能以及室温与900℃摩擦学性能的影响.结果表明:合金中W含量较低时形成单相面心立方(FCC)固溶体,W含量较高时会促进金属间化合物μ相的形成,随着W含量提升,合金显微组织由FCC胞状树枝晶(x=0.25)转变为FCC树枝晶及晶间层片状(FCC+μ)共晶组织(x=0.5、0.75),最后转变为FCC基体上分布的粗大树枝状μ相(x=1.0).由于W元素的固溶强化及原位生成金属间化合物μ相的第二相强化作用,使合金的强度和硬度等力学性能显著增加的同时塑性降低.在试验载荷为10 N,滑动速度0.3 m/s的测试条件下,CoCrFeNiW_(x)系列高熵合金与Si_(3)N_(4)陶瓷球配副时的球-盘摩擦试验结果表明:W元素的添加显著改善了合金的室温耐磨性,但对摩擦系数的影响较小;而900℃摩擦时,摩擦表面形成的多元复合氧化物摩擦釉质层具有良好的减摩抗磨作用,特别是W元素氧化产生的WO_(3)显著降低了摩擦系数,从而显著提升了合金的高温摩擦磨损性能.本文中研究的系列高熵合金中,CoCrFeNiW_(0.75)高熵合金室温下的屈服强度为863 MPa,抗压强度达1 250 MPa,900℃仍能保持446 HV的硬度,并在室温及900℃下均具有良好的摩擦磨损性能,具有良好的工程应用前景.
In aerospace and aviation industry,there is an urgent need for the materials with good mechanical properties wear resistance performance and self-lubricating properties at high temperatures.High entropy alloys (HEAs),also known as multi-principal element alloys are a kind of novel metal materials that contain five or more elements in near equiatomic proportions with four core effects:high entropy,sluggish diffusion,severe lattice distortion,and cocktail effects.Because of their unconventional structures,the HEAs exhibit excellent strength,hardness,fracture toughness wear resistance and high temperature stability,all these advantages make HEAs have promising for high temperature applications in the field of aerospace and equipment manufacturing.In this study,in order to obtain a HEA with excellent mechanical properties and tribological properties,a series of CoCrFeNiW_(x) (x=0.25,0.5,0.75 and 1.0) HEAs were prepared by vacuum arc melting.The effects of W content on the crystal structure,microstructure,mechanical properties and tribological properties of CoCrFeNiW_(x) HEAs at room temperature as well as 900℃were studied.The experimental results suggested that single-phase face-centered cubic(FCC) solid solution was formed in the alloy with low W content,and the intermetallic compoundμ-phase was promoted when the W content was higher than x=0.25.With the increase of W content,the microstructure of the CoCrFeNiW_(x) HEAs evolved from single-phase cellular dendritic FCC structure (x=0.25) to dendritic FCC plus interdendritic lamellar (FCC+μ) eutectic structure (x=0.5,0.75),and then to coarse dendriticμphase on FCC matrix (x=1.0).Due to the effect of solution strengthen of W atoms and the precipitation strengthen of the in-situ formed intermetallic compoundμ-phase,the mechanical properties such as yield strength and compressive strength of the HEAs are significantly increased while the plasticity is decreased.The Vickers hardness of the CoCrFeNiW_(x) HEAs were improved significantly with the increasing W content
作者
王世伟
周晖
徐莺歌
张凯锋
冯凯
WANG Shiwei;ZHOU Huil;XU Yingge;ZHANG Kaifeng;FENG Kai(National Key Laboratory of Science and Technology on Vacuμm Technology and Physics,Lanzhou Institute of Physics,CAST,Gansu Lanzhou 730000,China;Department of Basic Subjects,Lanzhou Institute of Technology,Gansu Lanzhou 730050,China)
出处
《摩擦学学报（中英文）》
EI
CAS
CSCD
北大核心
2024年第3期312-322,共11页
Tribology
基金
真空技术与物理国防科技重点实验室基金项目(HTKJ2020KL510005)
甘肃省自然科学基金项目(20JR5RA081)资助。
